Avocado harvest close to projection as La Niña looms

Kevin Hecteman

Special to the Village News

A largely drama-free avocado-growing season has all but ended, with the crop close to meeting midseason projections.

As of last week, the 2020-2021 season – which started Nov. 1, 2020 – had seen 263.5 million pounds of fruit come off the trees, according to figures from the California Avocado Commission. That's just below the 265 million pounds forecast in the commission's April survey of growers and handlers. By contrast, the 2019-2020 growing season – which ran into the beginning of the COVID-19 pandemic – ended with 375.5 million pounds, according to commission figures.

In Northern San Diego County, Fallbrook-based grove manager Charley Wolk said this year's crop and next year's are feeling the effects of inconsistent weather earlier in 2021. Some groves in the area had no fruit to harvest, he said.

"We didn't have a freeze or anything," Wolk said. "We just had weather that was not conducive to growing avocados." That included runs of five to 10 days with below-average temperatures, followed by three or four days of above-average days, followed by more below-average days.

"It kept doing that through the spring and the pollination season," Wolk said. "(With) the fruit that was for this year, that unstable weather plus some windstorms knocked all the fruit on the ground."

He said the extent of wind damage depended on which way groves were facing; avocado farms facing west fared better than their eastern-facing counterparts.

The wide temperature swings prevented the trees from getting into a rhythm.

"The trees were confused," Wolk said. "They didn't know if it was springtime or winter. The trees didn't know what to do because of the widespread unstable weather, specifically the temperatures."

The consistently inconsistent weather may have dented 2022 production, Wolk said.

"The flowers that we had in the spring, which would be the fruit for next year – because of that unstable weather, the flowers fell on the ground," Wolk said, noting that the weather may have made it difficult for bees to fly and flowers to open. "They never got pollinated."

Even so, Wolk was quick to emphasize that, overall, he expects the 2022 crop to surpass the 2021 total.

Ventura County, the top avocado-producing county in California, saw no major weather disasters this season, said Ben Faber, a University of California Cooperative Extension farm advisor based in Ventura.

Santa Ana winds and mild temperatures prevailed last week. "This is nothing," Faber said.

"The last two years previously, we've had those heat waves" in mid-to-late summer, Faber added. "They have just done awful things to not just the crop, but to the trees. It's actually outright killed young trees. We've had no acts of God like that here in the last 12 months."

There is one potential issue lurking in the Pacific Ocean: La Niña, which tends to push the storm track farther north. This pattern, Faber said, tends to bring "typically low rainfall, which typically reflect low humidity, which means it's a greater likelihood that we get cold spells. We just need to be on guard for that."

There is no set temperature at which frost becomes a concern; Faber noted the temperature and dew point in the forecast will tell the tale. Dew point is the temperature at which the air reaches a relative humidity of 100% and water droplets begin to condense into dew.

"You know that when the sun goes down, it could pretty rapidly go from 35 degrees, 34 degrees, boom, down to 26 degrees in just a few hours," Faber said. "You're looking at what the potential is for that nighttime temperature."

A solution may lie in overhead sprinklers, typically used when the thermometer is at the other extreme.

"It's not irrigation," Faber said. "It's not applying water to meet the transpirational needs, but it's water applied to the leaves in order to cool them. These techniques can be very, very effective for heat mitigation, but they could also be used for frost control."

As most of the state is still in extreme or exceptional drought, water may pose a challenge barring a wet winter. Wolk's home turf, San Diego County, may be in a better spot than most; the U.S. Drought Monitor showed moderate drought in the county as of last week.

"Southern California has water," Wolk said, because "Southern California, over the recent decades, has invested in reliability, which may not be the case in other parts of the state." Availability is not the issue, he added – "it's managing the cost of the water." That means being more precise and taking advantage of modern irrigation technology, Wolk said.

"Today's sensors are, to me, almost unbelievable," Wolk said. "They sense everything – salinity, moisture, the spectrum of the information you need to irrigate." Some of these, he added, are tied to computers with preset levels; the water comes on when these levels are reached. Wolk noted that the systems still need to be checked in the grove multiple times per week.

Water, Faber said, may be the driving force behind avocados' northerly migration. In 2019, the latest year for which county crop reports are available, Ventura County had 16,491 acres of avocado groves, while San Diego County had 14,946.

"The bulk of it is north of Los Angeles now," Faber said. "That's where cheaper water is. That's the thing about Ventura; there's a lot of deep groundwater that's available." With Santa Barbara and San Luis Obispo counties added, some 70% to 75% of California avocado production now takes place north of the City of Angels, Faber said.

Kevin Hecteman is an assistant editor of Ag Alert. He may be contacted at [email protected].

The article is reprinted courtesy of the California Farm Bureau Federation.